/*
 * Copyright (c) 2013, OpenCloudDB/MyCAT and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software;Designed and Developed mainly by many Chinese 
 * opensource volunteers. you can redistribute it and/or modify it under the 
 * terms of the GNU General Public License version 2 only, as published by the
 * Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 * 
 * Any questions about this component can be directed to it's project Web address 
 * https://code.google.com/p/opencloudb/.
 *
 */
package org.opencloudb.config.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;

/**
 * @author mycat
 */
public class OrderRetainingMap<K, V> extends HashMap<K, V> {
    private static final long serialVersionUID = 1L;

    private Set<K> keyOrder = new ArraySet<K>();
    private List<V> valueOrder = new ArrayList<V>();

    @Override
    public V put(K key, V value) {
        keyOrder.add(key);
        valueOrder.add(value);
        return super.put(key, value);
    }

    @Override
    public Collection<V> values() {
        return Collections.unmodifiableList(valueOrder);
    }

    @Override
    public Set<K> keySet() {
        return Collections.unmodifiableSet(keyOrder);
    }

    @Override
    public Set<Entry<K, V>> entrySet() {
        throw new UnsupportedOperationException();
    }

    /**
     * @author mycat
     */
    private static class ArraySet<T> extends ArrayList<T> implements Set<T> {

        private static final long serialVersionUID = 1L;
    }

}